The unidentified body was being removed from the ship. Before the body was found on Sunday afternoon, there were at least 20 people missing.

Earlier, Italian officials said it was possible that unregistered passengers had been aboard when the Concordia struck a reef off Giglio. Only eight of the 13 bodies so far found have been identified.

"There could have been X persons who we don't know about who were inside, who were clandestine" passengers aboard the ship, Franco Gabrielli, the national civil protection official in charge of the rescue effort, told reporters at a briefing on the island of Giglio, where the ship, with 4,200 people aboard rammed a reef and sliced open its hull before turning over on its side.

Mr Gabrielli said that relatives of a Hungarian woman have told Italian authorities that she had telephoned them from aboard the ship and that they have not heard from her since the accident. He said it was possible that a woman's body pulled from the wreckage by divers yesterday might be that of the unregistered passenger.

But the identity of that body and of three male bodies, all badly decomposed after days in the water, have yet to be established. Mr Gabrielli said they have identified the other eight bodies: four French, an Italian, a Hungarian, a German and a Spanish national.

The Italian captain, Francesco Schettino, is under house arrest as prosecutors investigate him for suspected manslaughter, causing a shipwreck and abandoning the ship while many were still aboard.

Operator Costa Crociere, a subsidiary of US-based Carnival Cruise Lines, has said that Capt Schettino had deviated without permission from the vessel's route in an apparent manoeuvre to sail close to the island and impress passengers.

Capt Schettino, despite audiotapes of his defying Coast Guard orders to scramble back aboard, has denied he abandoned ship while hundreds of passengers were desperately trying to get off the capsizing vessel. He has said he co-ordinated the rescue from aboard a lifeboat and then from the shore.